Content protection
AssigneeNagravision Sarl
InventorsChristian Schwarz, Andre Nicoulin, Didier Hunacek
Life of this patent
Estimating the term…
Abstract
Devices, servers, systems and methods for content protection are provided. Disclosed embodiments improve temporal granularity of controlling access to the protected content and increase resilience against attacks attempting to prevent re-evaluation of conditions of access. Enforcement of re-evaluation may be based on the receipt and/or verification of tokens. In some embodiments, re-evaluation is enforced by periodically rendering content keys required for content decryption unuseable and/or clearing content keys already in use.
Claims16
A method of decrypting encrypted media content, the method comprising:
- (a) receiving an encrypted media content stream on a client device;
- (b) receiving an encrypted content key for decrypting the encrypted media content;
- (c) authenticating and then decrypting the encrypted content key;
- (d) decrypting a predefined portion of the encrypted media content stream with the content key;
- (e) clearing the content key when decryption of the predefined portion is complete;
- and
- (f) repeating steps (b) to (e) to decrypt a next predefined portion of the encrypted media content stream,
- wherein the decrypting is performed by a descrambler having the content key loaded in a register thereof.
A method of decrypting encrypted media content, the method comprising:
- (a) receiving an encrypted media content stream on a server;
- (b) receiving an encrypted content key for decrypting the encrypted media content;
- (c) authenticating and then decrypting the encrypted content key;
- (d) decrypting a predefined portion of the encrypted media content stream with the content key;
- (e) clearing the content key when decryption of the predefined portion is complete;
- and
- (f) repeating steps (b) to (e) to decrypt a next predefined portion of the encrypted media content stream,
- wherein the decrypting is performed by a descrambler having the content key loaded in a register thereof.
A non-transitory computer readable medium having stored thereon a program that when executed by a computer causes the computer to implement a method of decrypting encrypted media content, the method comprising:
- (a) receiving an encrypted media content stream on a client device or a server;
- (b) receiving an encrypted content key for decrypting the encrypted media content;
- (c) authenticating and then decrypting the encrypted content key;
- (d) decrypting a predefined portion of the encrypted media content stream with the content key;
- (e) clearing the content key when decryption of the predefined portion is complete;
- and
- (f) repeating steps (b) to (e) to decrypt a next predefined portion of the encrypted media content stream,
- wherein the decrypting is performed by a descrambler having the content key loaded in a register thereof.
Dependencies are inferred from the claim text.